The present invention relates to a radiation sensor which contains fluorescible material and in which radiation to be detected is absorbed to produce fluorescent light, which light is conducted onto the photosensitive surface of a detector.
In the manufacture of sensors for the short-wave spectral region (UV), it becomes a disturbingly noticeable fact that on the one hand the quantum efficiency of conventional detectors progressively decreases with decrease in the wavelength and, at the same time, it becomes increasingly difficult to find material suitable for concentrating or focusing the radiation.
It is known that quantum yield of semiconductor radiation sensors which perform worse in the direction toward short wavelengths, can be improved by arranging in front of the photoelectric detector proper a layer containing a fluorescible material which is excited by radiation to be detected. The fluorescent light thereby produced is then detected by a detector which is sensitive to the fluorescence wavelength. An x-ray sensitive sensor of this construction has been described, for instance in West German published patent application (Offenlegungsschrift) OS No. 2,041,523.
In this known sensor the size of the detected radiation cone is determined by the area of the photo-sensitive region of the detector. There is no collection or concentration of radiation to be detected, prior to impingement on the detector.
Solar-energy collectors for concentration of sunlight are known in the form of plastic plates which incorporate fluorescible dyestuffs. In such plates, the fluorescent radiation excited by the sunlight is conducted in part by inner total reflection at the top and/or bottom surface of the plate, to end surfaces which are partially covered with a reflective covering or on which solar cells are arranged for converting the fluorescent radiation into electric current.
In this way, a certain concentration can be obtained, for sunlight incident on the surfaces of the plates, the concentration being approximately in the ratio of the top or bottom surface area of the plate to the end-surface area. Despite this size reduction for the received beam, relatively large-area detectors are required for coverage of at least one of the end surfaces, for conversion into electricity. Further, such plates are rigid and unwieldy and are therefore unsuitable for sensor uses.